This invention relates to a jet engine and more particularly to a method and apparatus for reducing noise during takeoff and landing of a jet airplane, wherein the thrust reverser mechanism is utilized to introduce ambient air by moving the aft portion of the cowling or nacelle rearwardly exposing the reverser cascades or apertures and retaining the reverser doors in the stowed position. When necessary or desired, the reverser doors or buckets may be deployed, and the thrust reverser will operate in normal fashion.
As the amount of air traffic has increased, people have become more aware of the damage and inconvenience of the noise. As a result some airports restrict the amount of traffic, and more and more airports are limiting the amount of noise allowed. In fact, the FAA has imposed noise limits on takeoff and landing, and further restrictions are in the offing.
Historically, as noted in the prior art, elaborate mechanisms have been developed to reduce the amount of noise, but these devices have been somewhat self-defeating, in that they increase the weight of the airplane, thereby decreasing the effective pay load, and they increase the mechanisms of the craft, resulting in a greater possibility of breakdown and increased cost.
Prior art known to the inventor includes:
U.S. Pat. No. 3,581,841 granted to Raynes on Jun. 8, 1971, which discloses thrust reversing and noise suppressing apparatus which includes tubular ejectors around a thrust nozzle from the sound-suppressing deployed position, the ejectors telescope relative to one another during normal flight and the doors are deployed.
U.S. Pat. No. 3,583,640 granted to MacDonald on Jun. 8, 1971, discloses vertically stacked thrust nozzles and thrust reversing doors opposite from the nozzles for movement between a stowed position adjacent to nozzles and a partially deployed position which deflects slipstream air against the exhaust gas, in a fully deployed position the doors abut and deflect the exhaust gas forwardly.
U.S. Pat. No. 3,591,085 granted to Medawar et.al on Jul. 6, 1971, discloses a sound suppressing and thrust reversing apparatus, wherein the shroud has an included ejector and reverser support ring nested for normal flight and extended for sound suppression and/or thrust reversing.
U.S. Pat. No. 3,710,890 granted to True et.al on Jan. 16, 1973, discloses an attachment for a jet engine, and an ejector shroud is closely spaced around the lobes, introducing large quantities of ambient air, reducing the air velocity attendant to the jet noise levels.
U.S. Pat. No. 3,614,037 granted to Vdolek on Oct. 19, 1971, discloses a combination thrust reverser and sound suppressor which is packaged together in a housing attached to the rear of the aircraft and the thrust reverser doors are located around the housing spaced between the sound suppressor chutes.
U.S. Pat. No. 3,749,316 granted to Tontini on Jul. 31, 1973, discloses a sound suppressing ejector nozzle which is positioned aft of the exhaust nozzle and defines, with the nozzle, inlet passages for a free stream of air.
U.S. Pat. No. 3,910,375 granted to Hache et.al on Oct. 7, 1975, discloses a jet engine silencer for an engine having a thrust nozzle, wherein the gas jet is placed in contact with air issuing from the central body portion of the silencer.
U.S. Pat. No. 5,154,052 granted to Giffin III et.al on Oct. 13, 1992, discloses an exhaust assembly for a gas turbine engine.
U.S. Pat. No. 5,826,794 granted to Rudolph on Oct. 27, 1998, discloses an aircraft scoop ejector nozzle for reducing exhaust noise in an intermediate bypass ratio turbo fan engine.
U.S. Pat. No. 5,884,472, granted to Presz, Jr. et.al on Mar. 23, 1999, discloses a noise suppressor comprising a mixing ring of alternating lobes attached to the engine""s tailpipe.
With the above-noted prior art and problems in mind, it is an object of the present invention to provide a method and apparatus for suppression of a jet engine utilizing the mechanisms already in place, in a different fashion to accomplish noise suppression.
It is another object of the present invention to take a standard jet engine including a thrust reverser, and by modifying the control, and therefore the relative location of the reverser mechanism, utilize the mechanism as a sound suppressor and a thrust augmenter.
Still a further object of the present invention is to utilize a currently available mechanisms on a jet engine, and by modifying their operation, reduce the noise generated thereby.